Printing process and product thereof



Patented Nov. 17, 1942 PRINTING PROCESS AND PRODUCT THEREOF J oseplm L.Switzer and Robert O. Switler, Cleveland, Ohio application August 2,1938, Divided and this application November 20, 1940, Serial No. 366,432

14 Claims. (Cl. 101-426) No Drawing. Original Serial No. 222,676.

print, when viewed in filtered ultra-violet lightaccurately portrays thetrue form, color, expression and general characteristics which areapparent when the original subject matter is viewed in normal visiblelight.

Another object and purpose of the present invention is to makeluminescent impresses, in which the effect of highlights and other lightsections in filtered ultra-violet light is produced by printing a.relatively large number of minute areas of light-producing fluorescentinks, allowing a relatively small portion of the white or otherlight-reflecting receiving surface to remain untreated, while the effectof darker sections in filtered ultra-violet light is produced byprinting a relatively small number of widely separated minute areas offluorescent inks, allowing broad expanses of the white receiving surfaceto remain untreated; this is in contra-distinction to the well-knownprocedure in orthodox color printing, by which the eifect of highlightsis produced by printing a relatively small number of widely separated,minute areas of light-absorbing colored inks, allowing broad expanses ofthe unprinted light-reflecting receiving surface to predominate, whilethe effect of darker tones is produced by printing a relatively largenumber of minute areas of light-absorbing colored inks, allowingarelatively small portion of the unprinted light-reflecting receivingsurface to show through.

A further object of the invention is to construct and arrange theink-supplying portions of the printing plates in such a manner that thenew reproduction media, namely, light-producing fluorescent inks, willbe applied in proper positions and quantity upon the receiving surfaceof the paper, so as to give a true and recognizable portrayal of theoriginal subject matter when the resultant print is observed under a newviewing condition, namely, filtered ultra-violet light.

The mu1ti=color or three-color reproduction printing of orthodox,non-fluorescent, colored inks, as generally practiced, comprises thesuccessive application of two or more diflerent colored inks, eachcapable of absorbing different wave-bands of incident white light. Suchinks are printedv in discontinuous minute areas upon a white receivingsurface, so that the composite unabsorbed incident light reflected froma given small section of the printed surface is decreased in intensityand narrowed in visible spectrum by each successive application, to theextent that said given area portrays the desired brilliancy and color.It, is an object of this invention to successively apply two or morefluorescent inks, each capable of fluorescing in different wavew bands;said inks are to be so printed in discontinuous minute areas upon awhite receiving surface that the composite light-emission from a givensmall section of the printed surface, during exposure to filteredultra-violet light, is increased in intensity and expanded in visiblespectrum by each successive application to the extent that said givenarea eifects the desired brightness and color of fluorescence Animportant purpose of this invention is to increase the range offluorescent tones and colors by using selected ligh -absorbing materialsin conjunction with light-producing, fluorescent inks; that is, to varythe fluorescent color of a print to any desired extent by printing anonfluorescent substance which has been chosen specifically to absorbcertain wave-lengths of the light-emission from the light-producingfluorescent inks. In practicing this invention, these selectedlight-absorbing substances are sometimes applied prior to thefluorescent printing; they are sometimes mixed directly with thefluorescent inks, and they are sometimes printed after the. fluorescentinks have been applied.

It is among the further objects of this invention to reproduce acomplete picture or other composition, which includes shadings, tones,etc., by printing fluorescent inks in multitudinous minute areas soarranged that the completed print, when viewed in filtered ultra-violetlight,

accurately portrays the true form, color, expression and generalcharacteristics which are apparent when the original subject matter isviewed in normal visible light; this luminescent reproduction is to bemade upon a receiving surface which also supports a satisfactorynon-fluorescent reproduction of another subject matter printed inorthodox colored inks, and so arranged as to substantially avoid anyinterference with the luminescent effect produced by the fluorescentreproduction when exposed to fluorescigenous radiant energy.

This invention further provides for the makin of duplicatlve luminescentreproductions which, under substantially invisible ultra-violet light,portray a decided effect of third-dimension because of the extremecontrast apparent when light-producing inks are printed on backgroundswhich are virtually unseen under ultra-violet rays, thus giving depth,realism, and all dimensions to luminescent reproductions ofthree-dimensional subject matters.

Lacquers of luminescent character are wellknown and their application byhand brushes in the painting of individual productions, pictorials orlettering, as desired, is likewise known. Many pigments used, as zinc orcalcium sulfides, have been of coarse size necessarily, because iffinely ground, they tend to lose their luminescent properties. Suchcoarse pigments cannot be used successfully for the purposes of thisinvention, as they pile or block the fine recesses of fractional-toneprinting surfaces and the like, and, furthermore, the vehiclesordinarily used for carrying the known luminescent materials are notworkable by such printing press surfaces because of their adversecharacteristics, as improper drying rate, improper viscosity and tack,possible attack on plate or offset transfer surfaces, etc. However, withnew fluorescent inks described herein as being compounded for thespecific purpose of printing minute dots, fine lines, delicatecheckerboard areas and other fractional-tone structures, it now becomespossible to make duplicative reproduction impresses in any desirednumber, without drying or distributing difliculties or attack on theplate or transfer surfaces, the product being beautifully luminescent inexposure to fluorescigenous radiant energy.

Heretofore, in the identification and crime de tection fields, it hasbeen known to apply a fluorescent mark to an article by block or lineprinting for the purpose of rapid identification of the article by thefluorescence of the mark in filtered ultra-violet light. The presentinvention, however, relates to the totally different art of duplicationwith fluorescent media of pictorial, advertising, and other subjectmatters of a graphic nature, and is to be clearly distinguished fromsuch well-known and obviously remote identification and crime detectionsystems in that it provides for the arrangement of multitudinous minuteareas of fluorescent inks on a receiving surface so that the completedimpress duplicates and accurately portrays, in filtered ultra-violetlight, the true form, color, expression and general characteristicswhich are apparent when the original subject matter is viewed in normalvisible light, this to be accomplished by special procedures hereindisclosed for applying new light-producing reproduction media ratherthan the light-absorbing media used in orthodox color printing.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following descriptionsetting forth in detail certain illustrative' embodiments of theinvention, these being indicative however, of but a few of the variousways in which the principles of the invention may be employed.

This application is a division of our co-pending application Serial No.222,676, filed August 2, 1938.

In the printing trade, as generally practiced,

subject matters which include shadings, tones, and highlights arereproduced by the application of light-absorbing colored inks inmultitudinous minute areas so arranged that the completed print portraysin normal visible light the true form, color, expression, and generalcharacteristics which are apparent when the original subject matter isviewed under similar lighting conditions. The term light-absorbing asherein used is intended to describe substantially nonfluorescentsubstances, such as black inks, orthodox coloring matters, and papers,each capable of absorbing certain wave-lengths of incident visiblelight. Such colored inks, for example, are normally efl'ective forreproduction purposes only when the incident rays of light striking theminclude some visible light between 4000 and 8000 Angstrom units inwave-length. Colored inks absorb a portion of the energy in this range,and reflect or transmit the balance, whereas the paper receiving surfaceupon which they are printed usually reflects a large proportion of thevisible light striking it.

Light-producing fluorescent inks may be differentiated from suchlight-absorbing inks in that the fluorescent inks are effective to amaximum degree only when the incident rays striking them include someenergy shorter than 4000 Angstrom units in wave-length, and they aremost effective when a large proportion of the visible light has beenfiltered out of the incident rays to provide a substantially unseenincident ray. The term light-producing" as herein used is intended todescribe certain fluorescent substances capable of converting incidentfluorescigenous radiant energy into visible light; that is, capable oftransforming-unseen wave-lengths shorter than 4000 Angstrom units intovisible light longer than 4000 Angstrom units in wavelength. X-raytubes, cathode tubes, and carbon arc equipment, for example, can be usedto produce fluorescigenous radiant energy to excite impresses of ourlight-producing fluorescent inks, but we generally employ mercury vaporlamps fitted with jackets of nickel oxide glass or darkcolored Corex, inaccordance with well-known practices in the vapor lamp industry, tosubstantially eliminate the visible light from the lamp and to pass onlythe invisible ultra-violet radiations desired.

The term light reflecting" as herein used is intended to describecertain substantially nonfluorescent substances, as white orlight-colored papers or pigments, capable of reflecting a relativelyhigh percentage of incident light striking them. Each tiny particle offluorescent ink applied to such a light-reflecting surface convertsinvisible ultra-violet light into visible light and exhibits maximumbrightness when its lightemission is substantially reflected by thesurface beneath. Thus, each particle of fluorescent ink printed upon aproper light-reflecting surface throws off a distinct beam of visiblelight during exposure to fluorescigenous radiant energy, and for thepurposes of this invention becomes a separate and distinct source ofvisible light requiring accurate placement upon the paper in the exactposition where a highlight is desired. When a luminescent impress uponsuch a lightrefiecting receiving surface is viewed under filteredultra-violet light, the unprinted portions of the surfac reflect thisincident light, but still appear to the observer to be very dark becausesuch rays are substantially unseen by the human eye.

The term highlight as herein used is defined as and intended to includethe lightest or brightest parts of a reproduction impress under theparticular lighting condition in which it is designed to be viewed. Induplicative luminescent printing, the greater the number of fluorescentparticles printed in a given area on a light-reflecting receivingsurface, the greater will be the re sultant intensity of fluorescencefrom that area, and the greater will be the apparent brilliancyof thehighlight in flltered ultraviolet light. Generally, increases inbrllliancy of fluorescent highlights may be accomplished by increasingthe size, number or thickness of the minute areas of fluorescent inkapplied per unit area of the surface, while decreasing same results inthe darkening of fluorescent shades; fluorescence brightness in anygiven section of the print is normally in a substantially directproportion to the size, number per unit of area and/or thickness of thefluorescent fractional- .tone structures in said section, or to thetotal volume of. fluorescent ink printed thereon.

For the purposes of this invention, we employ fluorescent materialswhich may be handled in the general manner of inks, and which are oftransparent or opaque character, as desired, and of a viscosity and tackworkable on press surfaces. The materials print as feasibly as orthodoxnon-fluorescent inks, without bleeding, piling, spreading, blurring,mottling, or becoming fuzzy, thus producing clear tones, shadings, and

other delicate reproductions, and setting with colored light-absorbingmedia. Luminescent reproduction procedures take many widely varied orms,some of which are described in the following illustrative, but in no waylimitative, examples:

Example 1.-In the practice of this invention, we may produce fluorescentduplicates of such non-fluorescent original sketches by printingfluorescent materials in the general manner, of an ink onlight-reflecting receiving surfaces, with mechanical supplying plates orscreens so manufactured, photographically or manually, that themultitudinous ink-supplying areas are relatively numerous on thosesections of the plate or screen designed to print fluorescenthighlights, and relatively sparse on those sections designed to producedarker fluorescent tones. During the making of theprinting surface, anydesired increase in th brightness of a highlight on any particularsection of the flnal print may be obtained by altering that portion ofthe printing surface so that the fractional-tone structures influorescent ink applied to the paper will be increased in number, sizeand/or thickness to eifect the increase in brightness of the highlightdesired. 'In a similar manner, any alteration in the printing surfacecausing any decrease in the suflicient quickness to-prevent offset, andto permit very rapid handling. As ink-like material operative withpress, oifset'or reticulated screen supplying surfaces, we usuallyprovide fluorescent agents in printing vehicles on the order of dryingoil bases, such as linseed varnishes, tung oils, etc. For examples: Aweak solution of sodium hydroxide is saturated withdiamino-stilbene-disulphonic-acid, and to one ounce of such solutionthere is added six ounces of glucose, and after thorough stirring, themixture is stirred into about nine ounces of alumina hydrate ground inclear linseed varnish No. 1, in proportion of 4 parts of hydrate to 5 ofthe varnish. Then,

three ounces of clear linseed-varnish No. 00 is added, and the mixtureis ground on the mill. Where desired, the alumina hydrate component maybe omitted, but generally it is preferable. Prints made from this ink,when exposed to fluorescigenous radiant energy, fluoresce whitish-blue.By substitution of berberine sulphate for thediamino-stilbene-di-sulphonic acid a product fluorescing yellow-greenmay be had, and by substitution oftetra-ethyl-diamino-ocarboxyphenyl-xanthenyl chloride, CzaHarNzOaCl, aproduct fluorescing red may be had, and by substitution of tetramethyldiamino diphenylketonimine hydrochloride, C1'1HazNaCLH20, a productfluorescing green may be had. A mixture of equalparts of the latter twoyields a product fluorescing orange, while a mixture of one part of thered fluorescing ink with eleven parts of the green fluorescing inkyields another yellow fluorescin ink.

The printing industry of today general reproduces originals provided inconvenient forms, such as sketches, photographs, paintings, designs,letterings, etc., to illustrate the form, colors, expressions andgeneral characteristics desired in the duplicates. Such sketches aresubstantially effective and useful only when viewed in normal visiblelight, because they are rendered in number, size and/or thickness of themulti tudinous minute areas of fluorescent ink applied to the paper,will result in a corresponding darkening of the shade in that particularsection of the print. In certain cases the plates we manufacture to meetthis requirement are negatives or photographic reversals of plates whichwould be used in reproducing the same subject matter with orthodoxlight-absorbing inks.

Example. 2.-Another procedure of making luminescent reproductionsconsists, firstly, in manually duplicating the original non-fluorescentcolored sketch, using commercial fluorescent water colors or oil colors,for example, so as to accurately portray in flltered ultra-violet lightthe true form, color, expression and general characteristics which areapparent when the non-fluorescent sketch is viewed in normal visiblelight; secondly, in flooding the resultant fluorescent sketch in adarkened room with intense ultraviolet light from which visibleradiations have been substantially eliminated; thirdly, in interposingan ultra-violet filter, such as a yellow K-2 Wratten gelatine, beforethe camera lens to pass the visible light from the fluorescent areas ofthe sketch, and-absorb the ultra-violet light reflected from the walls,untreated portions of the sketch, etc.; fourthly, in interposing anyreticulated half-tone or other screen required for the making of theparticular type of printing plate to be used, whether for intaglio,relief, planographic, or other printing; flfthly, in photographing thefluorescence of the sketch, and when more than one fluorescent color isto be printed, successively exposing a series of sensitized surfaces,using color separation screens to separate different ranges of thevisible light produced by the different fluorescent paints used on thesketch; sixthly, in making the mechanical printing surfaces by exposingsensitized plates through the resultant photographic images; seventhly,in applying, by means of the prepared printing surfaces, inks whichfluoresce in ranges identical to the ranges produced by the fluorescentmaterials on the fluorescent sketch, automatically placing thefluorescent inks in positions corresponding to the fluorescent sectionsof the sketch; and eighthly, during said application, in constantlychecking the reproductions in darkness under filtered ultra-violet lightto make certain that the plate is in proper register, and is supplying asufllcient quantity of fluorescent agent at all times.

If red fluorescing and whitish-blue fluorescing inks be used in such areproduction, brilliant fluorescent re'd highlights are produced bycrowding together a suflicient number of minute areas of the redfluorescing ink on a given section of the paper, while brilliantfluorescing whitishblue highlights are produced by crowding together asuflicient number of the proper sized areas of whitish-blue fluorescingink-to give the desired intensity in that section. If any given sectionof the reproduction calls for a brilliant fluorescing pink highlight, asuflicient number of minute areas of whitish-blue fluorescing ink areprinted between areas of red fluorescing inks to produce the desiredshade of fluorescent pink, The red fluorescing areas emit beams of redlight during exposure to fluorescigenous radiant energy, while thewhitish-blue fluorescing areas emit beams of whitish-blue light, withthe result that the eye perceives that part of the composition as abrilliant pink highlight. Thus, it is seen that the composite of thelight-emission from a given section of the receiving surface may beincreased in intensity as well as in color range by successiveapplications of additional fluorescent inks to the extent that thedesired brightness and color of fluorescence are effected in saidsection.

Where the red fluorescing and whitish-blue fluorescing inks are used,the fluorescent shades may be varied widely from blue to orchid, topink, to red, by altering the comparative quantity of the two differentfluorescent inks printed in a given area, as well as by altering therelative positions of the different fluorescing areas. If thefluorescing red areas predominate in size, num her, or thickness, or thefluorescing red dots have been printed last and have been so placed asto partially over-lap'the blue fluorescing dots, the shade willpredominate on the red fluorescing side, and vice versa. Therefore, itis readily seen that the composite of the light-emission from any givengroup upon exposure to fluorescigenous radiant energy is widely alteredin intensity and color range by alterations in the relative positions ofthe minute areas of different fluorescent inks. A very wide range ofsuch fluorescent tonal gradations may be produced by such alterations,through the use of any plurality of inks fluorescing in substantiallydifferent colors. Generally speaking, the results obtained aresubstantially the same as those resulting when beams of diferent coloredlight are blended. If green fluorescing and whitish-blue fluorescinginks be printed, alterations in the relative positions of the two seriesof dots result in variations from fluorescing green to greenish-white,to cold white, to bluish-white, to blue, while corresponding alterationsin the relative positions of minute areas of green fluorescing andorange fluorescing inks result in variations from beautiful fluorescentshades of green to yellow green, to yellow, to chrome, to orange.correspondingly, the alterations above-described may result in a widerange of fluorescent chromes and fluorescent oranges when fluorescingyellow and fluorescing red inks are printed. i

If'three different fluorescing inks, such as fluorescing blue,fluorescing yellow and fluorescing red, are printed, it is possible toproduce fluoresing the extent to which the different series of I dotsare superimposed one over another, and by altering the relative size,number and thickness of the minute areas of the different fluorescentinks. Through the use of the three above-mentioned fluorescent inks, itis possible to produce printed areas from which the compositelightemission. during exposure to fluorescigenous radiant energy isperceived by the eye as almost a pure white, and it is interesting tonote when this is accomplished that the different dots are placed insuperimposed positions substantially similar to those which produceblack when printed in the orthodox light-absorbing red, yellow and bluecolored inks used in ordinary color reproductions.

Example 3.It has often been found necessary to produce a luminescentprint which has a complete composition in daylight, and which alsoportrays a complete and sometimes different fluorescent composition whenviewed in filtered ultra-violet light. This is accomplished by-theprinting of ink materials providing the necessary fluorescent agents, inmultitudinous minute areas so arranged that the completed print, duringexposure to fluorescigenous radiant energy, accurately portrays the trueform, color, expression and general characteristics which are apparentin the original subject matter when it is viewed in visible light; saidsurface also receiving a satisfactory non-fluorescent reproductionimpress printed in orthodox colored inks, so arranged as tosubstantially avoid any interference with the luminescent effectproduced by the fluorescent impress when exposed to fluorescigenousradiant energy. The techniques used in producing such a result includethe placement of the minute areas of fluorescent inks on the paperbetween the dots of non-fluorescent light-absorbing colored inks, aswell as the partial superimposition of the fluorescing dots over thenon-fluorescent dots in cases where the non-fluorescing inks are verylightcoiored. The extent to which the fluorescent and non-fluorescentseries of dots are over-lapped is determined by the extent to which itis desired that the fluorescence be altered in color and intensity bythe light-absorbing colored areas.

The specific steps involved in accomplishing the above may consist,firstly, in manually constructing a sketch which includes the desiredfluorescent composition painted with commercial fluorescent artist oils,as well as a satisfactory non-fluorescent rendition of another subjectmatter painted in conventional light-absorbing non-fluorescent artistcolors so arranged and constructed as to substantially avoid anyinterference with the luminescent effect produced by the fluorescentcomposition when exposed to fluorescigenous radiant energy; secondly, inphotographing and reproducing the fluorescent rendition of the preparedsketch by the methods and steps outlined in Example 2; and thirdly, inphotographing the resultant sketch in visible light, using orthodoxcolor separation screens and half-tone screens, making plates from theresultant photographic images, and printing, by means of the preparedplates, non-fluorescent colored inks which match the non-fluorescentcolors used on the sketch.

Example 4.Although it is the general practice to print duplicativeluminescent reproductions upon a white paper stock which is a goodreflector of light, an extended embodiment of this invenrequires theaddition, before application of the fluorescent ink, of an agent such aslithopone,-

which is a good reflector of the light produced by the fluorescentagent. Such a mixture then acts independently of the colored backgroundand reflects to the eye of the observer a high percentage of thelight-emission produced by the fluorescent agent during exposure tofluorescigenous radiant energy.

Example 5.As a further means of increasing the range of fluorescentcolors available, and of accurately controlling the color and intensityof fluorescence on. a duplicative reproduction impress, we may apply inkmaterials providin fluorescent agents as well as agents capable ofabsorbing certain wave-lengths of the light produced by the fluorescentagent during excitation with fluorescigenous radiant energy. Forexample, we may add a small amount of ultramarine blue pigment, groundin any convenient printing carrier such as linseed varnish, to a largeamount of white fluorescing ink; the areas printed with such acombination ink throw off light which is deep blue in color rather thanwhite upon exposure to filtered ultra-violet light. The ultramarine bluepigment. performs the subtractive function of absorbing a part of thelight-emission from the white fluorescing ink,and the additionalfunction of reflecting the blue portion of the light-emission from thewhite fluorescing ink. In the same manner, we may add a small amount ofnon-fluorescent light-absorbing transparent yellow pigment, ground in aprinting carrier, toa large amount of green fluorescing ink to obtain aresultant print which fluoresces lemon yellow.

Example 6.-It has been found in practice that a further important meansof controlling the color and intensity of the light-emission from aduplicative fluorescent reproduction impress may be exercised by carefulselection of a receiving surface. capable of absorbing certain of thewavelengths of light emitted by the fluorescing inks printed over thatreceiving surface. For instance, we may print a brilliantly fluorescingred ink over a carefully selected non-fluorescent light-absorbing lightblue receiving surface to obtain an impress which fluoresces in abeautiful orchid or lavender. In this case, the light blue receivingsurface absorbs certain of the longer wave-lengths of the light emittedby the red fluorescing inks, and reflects a large portion of the shorterwavelengths, such as the blue.

Example 7.-A further refinement of our invention, related to anotherimportant means of controlling the color and intensity of fluorescencefrom a duplicative reproduction'impresa.entails the application ofinkmaterial providing fluores- .rescent blue dots, red where superimposedover cent agents upon receiving surfaces which also receive impressionsof non-fluorescent light-absorbing colored inks capable of absorbingcertain of the wave-bands of light produced by the fluorescing areas.For. instance, it may be necessary to produce a fluorescent print,certain sections of which must fluoresce yellow and other sections ofwhich must fluoresce a grass green. This may be accomplished by firstprinting a non-fluorescent light-absorbing transparent green ink inmultitudinous minute areas on that section of the paper which mustfluoresce grass green in the flnished print, and then printingmultitudinous minute areas of yellow fluorescing ink over thelight-absorbing green areas, the extent of superimposition in any givenarea depending upon the extent to which the fluorescent shade in thatarea must be altered toward the green side. The effect of this doubleprinting on such sections of the reproduction will be a green oryellow-green fluorescence, as desired, since the non-fluorescent greenareas will tend to absorb a portion of the light-emission from theyellow fluorescing ink, and largely reflect the green light emitted bysame. Naturally, the desired intensity of yellow fluorescence on thosesections of the print which must fluoresce yellow is obtained byprinting yellow fluorescing ink alone, in minute areas of .proper sizeand sumcient'number.

Example 8.-We may further control the fluorescence of a reproductionimpress by using a very carefully selected receiving surface which isitself fluorescent to the desired extent. For example, certaincommercial yellow papers may be employed as some of them are fluorescentdue to coloration during manufacture with 'a fluorescent dyestuff, suchas tetramethyl-diamino-dlphenylketonimine-hydrochloride. A paper so dyedwill fluoresce green in filtered ultra-violet light, and if weover-print same with an orangefluorescing ink, the fluorescence of theresultant impress will be yellow; overprinting with blue fluorescing inkresults in a cold white fluorescing impress. Rather intense light may beemitted by such a fluorescent paper during exposure to fluorescigenousradiant energy, and thus still another modifled means of fluorescencecontrol entails overprinting same with light-absorbing colored inkscapable of absorbing certain selected wave-bands of the light emited bythe fluorescent surface. A non-fluorescent transparent blue ink printedover the above-described fluorescent receiving surface will modify thegreen fluorescence of the paper posure. For example, we may printyellow, blue,

and red non-fluorescent colored inks, and overprint with whitefluorescing ink. Where the fluorescent ink is applied directly to thelight-reflecting receiving surface, its fluorescence will be vividwhite; it will fluoresce yellow where superimposed over thenon-fluorescent yellow dots,- deep'blue where superimposed over thenon-fluothe non-fluorescent red dots, etc.

It is to be understood that many omissions, alterations, andreplacements in the procedures employed, materials used, and otherphases of the invention described herein may be made by those skilled inthe nearest associated arts without detuted for paper. As a furtherexample, luminescent reproduction of each different composition bydifferent printing methods naturally necessitates wide variation in thephysical characteris'- tics of the plate, transfer, reticulated screenor other printing surface, to provide for the required number, size,thickness and positioning of the multitudinous minute dots, fine linesand other delicate and critical gradations of fluorescent inks. Theprinting of small quantities of luminescent impresses by suchspecialized methods as the silk screen printing process, for instance,is obviously within the comprehension of the invention.

We, therefore, claim:

1. A process of making duplicative reproduction impresses which areluminescent in exposure to fluorescigenous radiant energy, of subjectmatters, the compositions of which include highlights and shading,comprising the application from a mechanical supplying surface to alight-reflecting receiving surface of material providing a fluorescentagent, in discontinuous placed relatively close together to produce theeffect of highlights and other light shades, and widely separated toproduce the effect of darker shades.

2. In a process of making duplicative reproduction impresses which areluminescent in exposure to filtered ultra-violet light, the step whichcomprises printing upon a light-reflecting receiving surfacediscontinuous areas of fluorescent ink so close together in a section ofthe receiving surface intended to appear as a highlight during suchexposure that the ink covers a major portion of the area of saidsection.

3. In a process of making duplicative fluo cent reproductions, the stepwhich comprises the printing of fluorescent inks upon a visiblelightreflecting receiving surface in fractional-tone structures inwhich, in any given section of the print, the quantity of ink per unitof area in said section is substantially directly proportional to thefluorescent brightness required in said section.

4. A process of making duplicative fluorescent reproductions comprisingthe printing of substantially opaque fluorescent inks upon a receivingsurface in minute areas substantially directly proportional in size, inany given section of the print, to the fluorescence brightness requiredin said section.

5. A process of making duplicative reproduction impresses, luminescentin exposure to fluorescigenous radiant ener y. of subject matters havinghighlights and shading comprising the application, from a mechanicalsupplying surface to a light-reflecting receiving surface, of materialproviding a fluorescent agent, said material being applied in fractionaltone structures substantially the reverse in area and position oflight-absorbing inks printed in the orthodox color reproduction of thesame subject matter 6. A duplicative fluorescent reproduction of a tonalsubject matter comprising an ink-receiving surface supportingfluorescent ink in fractionaltone structures substantially the reversein area and position of non-fluorescent tone structures printed in theorthodox color reproduction of the same subject matter.

7. A process of making fluorescent reproductions comprising the printingupon discontinuous areas of a receiving surface of a relatively largevolume of fluorescent ink per unit area of surface in sections designedto simulate highlights and other light. shades during exposure tofluorescigenous radiant energy, and a relatively small volume offluorescent'ink per unit area in sections designed to simulate thedarker shades during such exposure;

' 8. In a process of making duplicative reproductions which areluminescent in exposure to fluorescigenous radiant energy, the stepcomprising the application from a mechanical supplyin surface to anygiven unit area of a receiving surface of fluorescent ink directlyproportional in volume to the fluorescence brightness required in saidarea during such exposure.

9. In fluorescence printing the step which comprises applying, todiscontinuous areas of a receiving surface, fluorescent ink covering amajor portion of each unit area of surface in sections intended torepresent highlights during exposure to fluorescigenous radiant energy.

10. A duplicative luminescent reproduction comprising an ink-receivingsurface coated, in any given unit area, with a volume of fluorescent inkdirectly proportional to the fluorescence brightness required in saidarea during exposure to fluorescigenous radiant energy.

11. In the art of printing fluorescent reproductions, the steps ofprinting upon a receiving sur-' face a first fractional tone structureof fluorescent ink emitting a first visible color, printing a secondfractional tone structure .of fluorescent ink emitting a second visiblecolor, and, in printing the said inks, varying the relative volumes ofthe first and second inks per unit of area of the receiving surface andadjusting the positions of the fractional tone structures of the flrstand second inks with respect to each other in the same units of area toproduce the shades desired in the units of area by the addition of thevisible colors emitted by the flrst and second inks.

12. .The method of printing fluorescent reproductions as deflned inclaim 11 including the steps of providing a relatively large totalvolume of the flrst and second inks per unit of area in a sectionrepresenting a highlight and a relatively small total volume of theflrst and second inks per unit of area in sections representing darksand shades.

13. In the art of printing fluorescent reproductions, the steps ofproviding a fluorescent receiving surface, printing a fluorescent inkupon said receiving surface in fractional tone structures to produce avisible shade comprising the addition of the visible colors of lightemitted by the receiving surface and the ink.

14. A duplicative luminescent reproduction impress comprising a surfacesuporting fluorescent tone structures covering a high percentage of thereceiving surface in sections intended to appear as highlights duringexposure to fluorescigenous radiant energy and covering a comparativelylow percentage of the receiving surface in sections intended to give theimpression of darker shades during such exposure.

. JOSEPH L. SWITZER.

ROBERT C. SWITZER.

55, claim 1, after 'discontin 1ousf' insert CERTiFICA'iE OF CORRECTION.7 Patent No. 2,502,615. I Noveniber l7, 1%2.

JOSEPH L. swITzER, ET AL.

It is hereby certified that error sppears in the printecispecificationof the above numbere d patent requiring correction asfollows; Page 1, first column, line 12, after "iight' insert a come;page 5, first column, line 68, for the word "general" read--general1y--,

--area s--; ,and that I the said Letters Patent should be read with thiscorrection therein that .the same may conform to the record of the casein the Patent Office. Signed and sealed this 29th day of December, A. D.l9l 2.

Henry Van Arsdale;

(Seal) Acting Commissioner of Patents.

' page 6, first column, line 1

